Process of manufacturing animal



June 20, 1944. Re. 22,500

PROCESS OF MANUFACTURING ANIMAL FEED COMPOSITIONS M. SHOELD Nw Q. m

Original Filed May 16, 1942 I has no food value.

Reissue d June 20, 1944 our!" PROCESS OF MANUFACTURING AHIMAL FEEDCOMPOSITIONS Mark Davison Chemical of Maryland Original Serial No.

Shoeld, Towson,

Corporation,

for reissue November 3,

9 Claims.

This invention relates to improvements in the manufacture of a mineralsupplement for animal feed.

In Patent No, 2,234,511, dated March 11, 1941, a process is disclosed inwhich superphosphate is calcined at temperatures of 600 C. to 800 C. toremove fluorine therefrom and toprovide a calcium andphosphorus-containing material available for animal feed.

It is found in the process of the present invention that an improved,nontoxic product is obtained by calcining superphosphate at temperaturesat which sulphuric acid, originally com bined with calcium as calciumsulphate, is driven off. This is accomplished without fusion orvolatilization of the available P205 in the superphosphate. and attemperatures above 800 C. Temperatures below fusion temperatures and inthe range of 800 C. to substantially 1200 or 1250 C. are preferablyemployed. Particularly good results are obtained at around l2-O0 C. orslightly above.

Sulphate ordinarily present in superphosphate By calcination ofsuperphosphate at temperatures above 800 C. the calcium and phosphorusof a given batch treated are retained to the extent of substantiallytheir original contents and in completely available form. As indicatedin the reaction represented by the following equation all of the calciumand phosphorus remains in the product and in a highly beneficial ratio:

Either ordinary den superphosphate or the granular superphosphate ofcommerce may be employed in the present process. The granularsuperphosphate is a product comprising nodular, globoid granules whichhave indurated and encrusted surfaces and which have a crushing strengthseveral times that of fully cured den superphosphate. At the highertemperatures employed in the present process, the granularsuperphosphate retains certain desirable properties which render it moreadvantageous for use than the ordinary den superphosphate. As found atlower temperatures, so also at the higher temperatures, more evenheating can be obtained, a more even contact of the heating medium withthe surfaces presented by the granules is made possible, and there ispractically no loss due to dust formation.

A means by which the present process is conducted economically and bywhich an excellent uniform final product is prepared is an inclinedrotary kiln into which superphosphate is fed at the high end and .istumbled and passed towards the low discharge end. A burner is providedat Mi, assignor to The a corporation No. 2,328,884, dated September '7,1943,

443,257, May

2. Application 16, 194 1943, Serial N0. 508,870

the lower end of the kiln and hot gasesare drawn through the kiln bymeans of an exhaust fan. The gases heat the tumbled phosphatic materialand calcine it to a point at which not only fluorine is removed, butalso sulphur existin as sulphat/e.

The single figure in the accompanying drawing represents a longitudinalsection of an apparatus suitable for carrying out the present process.

In the drawing, numeral l designates a hopper to which is fedsuperphosphate by means of a clam shell bucket or other suitable means,not shown. The hopper l is shown partially loaded with superphosphate,as indicated at 2. In the bottom of the hopper i lies a screw conveyor3, which is adapted to discharge superphosphate through an outlet l intoa chute 5. The chute 5 is closed by means of a hinged door 5.

The feed screw 3 is adapted to be driven by means of a motor I which,through a reduction gearing 8, drives a variable speed transmission 9.At ID in the chute 5 is shown superphosphate which passes down the chute5 and through a discharge end I l of the chute 5 into a rotary calcinerindicated generally by the numeral 12. The rotary calciner has its axisat a slant to the horizontal, having a high end l3 into which thesuperphosphate to be calcined is delivered, and a lower end M from whichthe calcined superphosphate is discharged. The superphosphate passingthrough the rotary calciner i2 is indicated by the numeral l5.

The rotary calciner I2 is provided with a refractory lining iii. Theupper end of the rotary calciner i2 is constricted, as indicated at H,and the chute 5 delivers the superphosphate to be calcined through aconstricted opening l8 formed at the upper end of the calciner.

Adapted to fit around the upper end of the calciner i2 is an exhaustbreeching l9 which, at its upper end is in communication with an exhaustpipe 20 that is connected to an exhaust fan 22. The exhaust fan 22delivers all exhaust gases through a stack 23.

In order to rotate the calciner l2, rings 24 are provided which areadapted to travel in rollers 25 mounted on supports 26. Motive power tomove the calciner l2 and give it the desired rotary motion is furnishedthrough a ring gear 21 driven by a pinion 28 which is mounted on a shaft29 of a motor 30. There may be reduction gearing between the motor 30and the pinion 28 if desired.

A refractory lined breeching 3i is shown at the lower end In of therotary calciner l2. This refractory lined breeching is provided with a.peels hole 32 through which the contents of the calciner may be viewed,and an aperture 33 I burner. The temperature of through which projects anozzle 34 of a gas or oil burner 35. At 86 is shown the flam of the thematerial in the caiciner is maintained above 800 C.

Secondary air is inducted into through the aperture 33 as the fluorinecontent of the superphosphate being treated.

The feed screw gum PIOI FiuriHI. ..QIIIIIIIIIIIIIIIIII basis of aninitial 100 pound sample of superphosphate. The P205, not beingvolatilized, its proportion in per cent may serve as a reference point.The calcined superphosphate runs 5.3 per cent S04 and 34.3 per centP205, and if no S04. were driven oiT, 34.3 per cent What is claimed is:4

1. In a process of manufacturing animal feed from superphosphates, thestep of calcining superphosphate attemperatures above 800 C. tosubstantially 1200 nally chemically combined as sulphate fromsuperphosphates, calcining the superphosphate at temperatures above 800C. to substantially 1200" C. until a major portion of sulphur originallychemically combined as sulphate in the crusted surfaces, at temperaturesabove 800 C. to substantially 1200 C. until a major portion combined assulphate in the superphosphate is substantiallycompletely eliminatedfrom the superphosphate.

5. In a, process of manufacturing animal feed from superphos-phates, thestep of calcining from superphosphates, the step of superphosphate atsubstantially 1200" C. until a major portion of sulphur originallycombined as sulphate in the superphosphate is superphosphate.

8. In a process of from is substantially completely eliminated from thesuperphospha 9. In a process of manufacturing animal feed fromsuperphosphates, the step 01' calcining

